1. Field of the Invention
The invention relates generally to roof systems and in particular to a roof system having a roof deck and a lightweight concrete poured over the roof deck.
2. Prior Art
FIG. 1 is a cross-sectional view of a conventional roofing system. This roofing system is described in U.S. Pat. No. 4,888,930, which is incorporated herein by reference. In FIG. 1, a roof deck 103 is attached to purlins 102 through fasteners 104. An insulation board 108 is attached to the deck 103 through fasteners 109, 110. A membrane 107 is placed over the top of the insulation board 108 to seal the roof. As shown in FIG. 2, the deck 103 maybe sealed by applying a caulk 112 at the deck joints. By sealing the deck 103, wind uplift forces WF are applied to the deck 103, and not the insulation board 108. The deck 103 can be rigidly fastened to the purlins 102 and thus withstand the uplift wind forces.
It is also known in the art to incorporate concrete into a roofing system in order to add stability to the roof. The concrete is placed between the insulation board and the roof deck. Holes are formed in the insulation board and when pressure is applied to the top of the insulation board, the concrete is forced up through the holes. Thus, the concrete provides a stable roof system. When uplift wind force is applied to the deck, the deck flexes causing the concrete to become detached from the deck and crack. This results in roof failure. There is a perceived need in the art for a concrete roof system that is resistant to uplift wind forces.